Apparatus for muffling the exhaust of gas-engines.



' PATENTEDMAY-Zii, 190

u w E. THOMSON. APPARATUS FOR MUFFLING THE EXHAUST OF'GA'S ENGINES.

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Ynvehof: E/i/w Thomson PATENTED MAY 28 E. THOMSON. APPARATUS FORMUPFLINGTHE EXHAUST 0F GAS ENGINES.

APPLICATION FILED AUG. 20, 1904.

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- /nvenlfior'. E/ihu 77101715017,

unnn' TAT S PATENT orrron Benn; THOMSON,

.or'SWAi rrScoTr, MASSACHUSETTS, ASSIGNOR TO QENERAL ELECTRIC COMPAN Y,A CORPORATION OF NEW YORK.

APPARATUS Fon-luu lume' THE EXHAUST oF GAS-ENGINES.

Specification of Letters I'atent.

Patented May 28, 1907.

Application filed August 20,1904. Serial No 221,472.

'. all whom it may concern: I

it knownthat I, ELIHU THOMSON, a citizen the United States, residing atSwampscott, countyof Essex, State of Massachusetts, have inventedcertain new and useful Improvements in Apparatus for Mufiiin the Exhaustof Gas-Engines, of which the fo low-,

mg is a specification.

. It is well known that the exhaust from as ID or explosion enginesproduces a disagreea le noise which partakes of the nature of anexplosion. To overcome this, ObJGCtlOh various kinds of mufflers havebeen provided which reduce the sound to a certain extent. As a I 5general proposition it may be stated that the more these mufliers reducethe sound, cs pecially when of small interior volume, the greater willbethe back pressure created thereby. In other words, all such mufilerscause considerable loss in efficiency, which less increases as the sounddecreases. I

have discove ed however that the sound of the exhaust can ,be decreasedto a point where it is unobjcctionable, .and this without the loss ofany substantial amount of energy, by breaking up each sound wave intoparts and delaying one or more parts behind the other orothers, so thattheirdeliveries to the point of .final discharge will lag in time onewith respect to the other or others. In

other Words, my invention depends upon the acoustic princlple ofinterference between impulses, and the sound wave for each exhaustdischarge, instead of having a high and well defined sharp peak, isflattened and. the discharge takesjplace' with a low hissing sound.

In waoticing my invention a chambered rece Jamie is provided having anumber of -ed discharge orifices, through which the eaust gases pass ontheir way to the point o. final discharge. These orifices are soarranged that practically speaking they all re ceive their portion ofthe exhaust products at the same time, and between them and the point offinal exhaust are one or more conduits or passages. The conduit orconduits are so arranged that it or they receive the exhaust from anrmber of different orifices, the latter however being so, arranged thatthe gasescaping from some of them has a longer path to travel than thegasescaping from the ries of orifices. Th

remaining orifice or orifices. In other words, one increment of gas orvapor due to a given impulse 'has to travel a certain distance in orc e1to escape, while another increment has to travel twice as far, and athird has to travel three times as far and so on. An elongated slot,tapering in width, might replace the see orifices are preferably, soarranged that either their area decreases toward the point of dischargeor, the area remaining the same, the number decreases. In either casethere would be a gradual decrease in the effective area of discharge.With the construction described tests show that there is virtuallynoback pressure, the

sound is reduced to a point where it is unobjectionable,-an'd themuflier asa whole is a smaller than those customarily employed for thesame size and type of engine.

1n the accompanying drawings, which illustrate an apparatus forpracticing the invention, Figure 1 is a view showing a gas engineconnected to a muffler of improved construction, the latter being shownin longitudinal section, Figs. 2 and 3 are detail views showing theconstruction of thedisks used to form the exhaust-conveying passages;Fig. 4 shows a slight modificationin the construction of the mufiier;Figs. 5 and 6'show the disks employed in forming the gas-conveyingpassage; Fig. 7 illustrates a construction wherein the orificesadmitting as to the elongated gas passage successive y decrease in areainstead of being of'the same size and 85 decreasing in number, as inFigs. 1 and 4," Fig. 8 is a diagram showing the effect of my improvedmufiier, and Fig. 9 isa further modification.

1 represents the engine, which may be of' any suitable character andoperated by gasolene, kerosene or other similar form of energy. Theexhaust from the engine is discharged into a chambered receptacle 2which in the resent illustration takes the form of a 9 5 tube t atisopen on the end adjacent to the engine and closed by suitable means,such as a cap 3, at the op osite end. This receptacle is rovided Wit/i la plurality of dischargeori ces 4, which orifices are graded from oneIoc' end of the receptacle to the other; that isto say, the orifices arethe most numerous near amount of gas or other vapor will 11 whichcorresponds in size tojthe external progressively l the inlet end of thetube 2 and Ina decrease in number toward the ca stead of decreasing thenumber orifices, the same number may bee loycd, but the size of theorifices should be ecreased from 1 the inlet toward the closed end ofthe tube 2. 5 By reason of this construction a later- IS.- charged atthe inlet'end of the' 'chambered receptacle than at the closed end.Surrounding the chambered receptacle is 2. cylinder 5 which engages theheads 6 and 7 that are mounte on the tube 2. These heads are securedinplace by suitable means such as the nut 8 and cap 3. The head 6 ismade solid, while the; 7 is perforated, as at 9, to permit-the productsof combustion or other vapor to escape. The interior of the cylinder 5is divided up by partitions 10 arranged to form anelongated passage. Theright-hand end of the assage or en adjacent to the engine is close whilethe outer end is in free communication with the orifices 9 thatcommunicate with the atmos )here.

In .igs. 2 and 3 are shown the disks for forming the spiral massageround the tube 2.

Each disk-is provi ed with a central opening diameter ofthe tube Thedisk is out, as at 12, to form the lip 13, which .lip is offset adistance equal to that between the disks when assembled as in Fig. 1.The disks are slip d over the tube and are bolted one to the ot ier andto the head 6 by bolts 14, suitable spacing devices such as tubes ornuts 16 being emplovcd to preserve the pro or relationship of the arts.When the dis 's are. assembled as in ig. 1-, a spiral passage is formedbeginning at the right-hand end of the mulller, which is incommunication with all' of: the on'ficess. Since all of the orificesreceive gas or other vapor in multi la and at substantially the sametime, it;fo ows that the increment of gas or other vapor issuing, fromthe orifices 17 has a greater distance to .travel than a similarincrement issuing from the orifice 18. In the present illustration thedifference in distance traveled is equal to the length of a )ath onceround the tube 2. It also follows t lat the distance traveled byincrements of gas or other vapor issuing from orifices nearer the inletend ofthe tube will have a correspondingly greater distance to travel.

The particular mulilcr illustrated has been used in honncction with anex )losion engine of the four-cycle type dcsignc to use either igasolcnc or kcroscnc, and to deliver between eight and ten horsepower.The numberand arrangement of the orifices can. be ehan d l to suit therequirements. In' the mu ler l under consideration the first turn of thespiral passage was provided with about ten holes, each from to a quarterinch in diameter, and the number of holes successively decreased towardthe lel'tdmud end. For convenience in constructing thc appnratus, holesof the same size may be cmplo ed for each turn, but I have found itrather more satisfactory to have the ol'iliccs on the right-hand cndsomewhat larger in diameter than those on the left-hand end.

in order to lighten the construction as much as possible and at the sametime to give it the requisite strength, it is desirable to employ aconstruction such as illustrated in Figs. 4 to 6 inclusive. .10represents a piece of tube or pipe which is provided with a coarsescrew-thread 21 to receive the d sks 22. The la ter are each providedwith a central opening 23 to receive the tube. 'lhcv are also split, asat 24, to permit of the disk being bent to form a spiral likev ascrewthrcad as shown in Fig. 5, the edge of one 5 disk being f-wvidcdwith an offset 25 to receive the ct go of the adjacent disk. Mounted onthe tube are heads .26 and 27, the

former being solid while the latter is rovidcd with perforations 28. Thetotal Toss-sectional area of these perforations should preferably exceedthe total cross-sectional area of the oriliccs in the tube 20.Surrounding the disks is a sheet-metal cylinder 29 that is retained inplace by a binding band 30 made of wire. It is to be noted that the wireslightly depresses the metal between the spirally arranged disks, whichholds the edges of the latter in place and rcvents them from rattling.'lhc Wirc-shou d be made of steel or equivalent material and be put onunder tension, and the ends suitably fastened.

The discharge end of the mufller may be rovided with a neck or nozzle 31as shown in 1 ig.'1, in order to direct the outgoing body of gas orvapor, but this is not essenl iio.

It will be seen from this construction that the length of the path ofgas escaping from the orifices 4 difl'elrs greatlv between theright-hand and the lei'hhand end ol' the null ller, the said pathssuccessively decreasing in length from right to lel' t. The rate oftravel of the gas impulse at ordinary atmospheric pressures and at aboutthe density of air. is about 1000 feetper second. With a (l('ll ('r finsthe rate is slower. The gas escnbiuf from the numerous holes at therigludmnd end has to travel practically ten times around the inner tube.2o. Another portion of the gas has to travel nine times urouud the tube,and another portion eight and 0 on. The gas csca )inglrom the hist holcn the. discharge en of the tube may pass directly through one of theorifices 28. or it' mu) pass a fraction of a turn or even more than i:turn round the tube.

' ,n'oises produced instead of passin stood t at this figure does nothowever rep- 'strated by coupling the engine to a dynamov i What I claimas new and desire to secure by Letters Patent of the United States, is,-I 1. devicedischarging gas or vaporin the form of impulses, incombination wi ii In Fig. 7 is shown asection of a tube 32 l wherein thegas-discharging orifices 33 successively decrease from right to left.

In Fig. 8 is shown diagrammatically the ,l effect whichis hrought aboutby the .use of l my im roved nniiiier. It is to be undertacle, anelongated municating with the receptacle and passage, resent the exactrelationship which exists. 34 represents an impulse from a gas en inegreatest at the inlet end of the receptacle.

2. A device discharging gas r vapor in the form of impulses, incombination with a muffler comprising a chambered receptacle, aplurality of orifices arranged to simultaneouslydischarge gas or vaporfrom the chamber, and means causing a greater retardation of the passageof gas or vaporbetween certain of the orifices charge than betweenothers."

3. A device discharging ga'js'or vapor in the form of impulses, incombination with a muffler comprising is closed at one end, dischargingthe contents when the muflier is not employed,,an 35 l represents therelationship between the arts l of the same impulse when lagged behinone another due to the effect of the muflier. In l other words, 34 reresents a sound wavehaving a well define and sharp peak, while 35represents .a sound wave which lasts longer, I but is much smoother andof lower pitch.

By actual test l have demonstrated that there is practically no backpressure when this muflier is employed. This is demonplurality oforifices forload and employing a volt and ampere meter of thereceptacle,

to make readings. With a constant load I have found that throwing themuffler on and of]? does not make a difierenceof more than one-half toone per cent. At a dista ceQof some thirty feet from the engine thesound of the exhaust is hardly noticeable, the

by the cams, etc. being the 4. In amufiier, the combination ofarecepprominent sounds. tacle having a plurality,of discharge orificesIt will be evident that the same principles. which decrease incrossesectional area as they of action are fulfilled if, instead ofletting the 'recede from the inlet to the receptacle, and gas flow inthe direction ,shown and. demeansfor causing the body ofgasor vaporscribed in Fig. 4, it moves .in the direction discharged by the orificesnearest the inlet to shown by the dotted arrow; in fact I find .travela-greater distance than those more ref that the arrangement works wellwhichever mote. L the direction of flow. 5. In a'muffler, thecombination of'a recep- A slight inddilication is shown in Fig. 9 inwhich there is a pipe 20 extending through one of the orifices islonger'than rom the other or others.

tacle, which is open at. one end and closed at the other, a lurality ofdischarge orifices the casing which is divided by a septum or containedin t partition 37, in advance of which are numerous holes, so that thegas enteringsuch ipe g directly therethrougi is turned aside into theouterspace, and traverses the elongated or spiral passage. The exitportion of the pipe 20 has a similar series of openings from the turnsofthe spiralpas sage, which is described in connection 'with' otherfigures, the area of the number of openings increasing toward theoutlet, preferably. .l t will thus be seen. that the arrangement, 5means for carrying ofl the gasor vapor from Fig. 9, isiiirtually thesame as Fig. 4, except 4 the tube, the said orifices that theconstruction is somewhat simplified to split up the sound waves andto-lag one and the gas finally escapes throughthe pipe portion withrespect to another. 20 at a point beyo'iid the partition 37. 7. In amuffler, the combination of an In accordance with the provisions of theelongated passage, with apluralit of orifices pa ent statutes I havedescribed the princi- 1 discharging into it in multiple, toe-said oripleof operation 01"" my invention together lfices being graded so thattheamount of gas with the apparatus-which I now consider to i or vaporpassin'g through them gradually represent the bestembodiment thereof,but l decreases toward the point of I desire to have it understood thatthe appal the passage. ratus shown is only illustrative, and that the i8. In a muflier, the combination of a chainout by'other means. I beredreceptacle arranged to receive the exthe closed end, a helicallyarranged assag e communicating with the orifices an so arranged that thegas "or vapor from some of the, orifices travels farther than fromothers. a 6. In a inufiier, the combination of atube which is open atone end and closed at the other, a plurality of discharge orifices forsaid I tube which decrease in effective cross sectional area toward theclosed end, and a invention can be carried and the point of final disereceptacle: which gradually decrease in total area from'theinlet towardand means actingdischarge of haust impulses from an engine, means for 5the tube and I'C'PPiHH or vapor [nun the ln'vnking up the continuity ofeacibimpuise uriiiws. Lhv tuhv uni} orifices heingurrangvd and othermeans coiiperating with the first to 5 tu ('uust' a part ur par-v; ofthe impuise to issue cause the sevural parts of the impulse to issuehniurv :muliwr pa [-1 w parts.-

5 sLwcessivr-iy. In NiLIll'SS whvruul, i lwwunio set my 15 9. In amufiier, the cumbination of u tube hand this lTl h (my ui' August 100-}.

having an admission and a QlOSGd end, orifices E111 HU 'IIIOBISON.arranged in the tubeyhvhihdischarge ga's 0r Nitllessvs: valfbr from thetube and are arranged in inul- JOHN A. Mchlixxus, JIL,

lo tip 6, and a spiral passage which surrounds & DuuAu) Mali. MUKILLOP.

